A New Approach to Analyzing Solar Coronal Spectra and Updated Collisional Ionization Equilibrium Calculations. Ii. Updated Ionization Rate Coefficients

Bryans, P.; Landi, E.; Savin, D. W.

doi:10.1088/0004-637x/691/2/1540

Cited by 240 publications

(314 citation statements)

References 36 publications

(172 reference statements)

Supporting

Mentioning

297

Contrasting

Order By: Relevance

“…Furthermore, the most relevant temperature for Fe XIV is 2.0×10 6 K, that of maximum abundance in ionisation equilibrium (Bryans et al 2009). At this Te the discrepancies are less than 20% between our calculated Υ and those of Tayal (2008) for all transitions.…”

Section: Effective Collision Strengthsmentioning

confidence: 52%

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Aggarwal

Keenan

2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Energies and lifetimes are reported for the lowest 136 levels of Fe XIV, belonging to the (1s 2 2s 2 2p 6 ) 3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 , 3s3p3d, 3p 2 3d, 3s3d 2 , 3p3d 2 and 3s 2 4 configurations. Additionally, radiative rates, oscillator strengths and line strengths are calculated for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions. Theoretical lifetimes determined from these radiative rates for most levels show satisfactory agreement with earlier calculations, as well as with measurements. Electron impact excitation collision strengths are also calculated with the Dirac atomic R-matrix code (DARC) over a wide energy range up to 260 Ryd. Furthermore, resonances have been resolved in a fine energy mesh to determine effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities. Results are listed for all 9180 transitions among the 136 levels over a wide range of electron temperatures, up to 10 7.1 K. Comparisons are made with available results in the literature, and the accuracy of the present data is assessed.

show abstract

Section: Effective Collision Strengthsmentioning

confidence: 52%

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Aggarwal

Keenan

2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Ionization Rate Coefficient ρ = 10 −6 i=5 i=0 a i x i cm 3 s −1 eV 3/2 , see Equations (3) and (5). (Bryans et al 2009). …”

Section: Discussionmentioning

confidence: 99%

Storage ring cross section measurements for electron impact ionization of Fe⁸⁺

Hahn

Becker

Bernhardt

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

We have measured electron impact ionization (EII) for Fe 7+ from the ionization threshold up to 1200 eV. The measurements were performed using the TSR heavy ion storage ring. The ions were stored long enough prior to measurement to remove most metastables, resulting in a beam of 94% ground state ions. Comparing with the previously recommended atomic data, we find that the Arnaud & Raymond (1992) cross section is up to about 40% larger than our measurement, with the largest discrepancies below about 400 eV. The cross section of Dere (2007) agrees to within 10%, which is about the magnitude of the experimental uncertainties. The remaining discrepancies between measurement and the most recent theory are likely due to shortcomings in the theoretical treatment of the excitation-autoionization contribution.

show abstract

“…For simplicity, we only compare the population of the first five levels (i.e., the ground level and the first four excited levels) of the Fe isonuclear sequence from He-like Fe xxv to Ne-like Fe xvii. The level populations are calculated in both codes using the same abundance table (Lodders et al 2009), the same ionization balance (Bryans et al 2009), and the same plasma temperature (where the ion concentration reaches its maximum). Figure B.1 shows the level population ratio with respect to the ground as a function of plasma density ranging from 10 6 m −3 to 10 20 m −3 (or 10 1 cm −3 to 10 14 cm −3 ).…”

Section: Density Diagnostics For the Ionized Outflow In Ngc 5548mentioning

confidence: 99%

Density diagnostics of ionized outflows in active galactic nuclei

Mao

Kaastra

Mehdipour

et al. 2017

A&A

View full text Add to dashboard Cite

Context. Ionized outflows in active galactic nuclei (AGNs) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their kinetic power as a cosmic feedback channel. Therefore, the impact of AGN outflows on their host galaxies is uncertain. However, when the density of the outflows is known, their distance can be immediately obtained from their modeled ionization parameters. Aims. We perform a theoretical study of density diagnostics of ionized outflows using absorption lines from metastable levels in Be-like to C-like cosmic abundant ions. Methods. With the new self-consistent PhotoIONization (PION) model in the SPEX code, we are able to calculate detailed level populations, including the ground and metastable levels. This enables us to determine under what physical conditions the metastable levels are significantly populated. We then identify characteristic lines from these metastable levels in the 1−2000 Å wavelength range. Results. In the broad density range of n H ∈ (10 6 , 10 20 ) m −3 , the metastable levels 2s2p ( 3 P 0−2 ) in Be-like ions can be significantly populated. For B-like ions, merely the first excited level 2s 2 2p ( 2 P 3/2 ) can be used as a density probe. For C-like ions, the first two excited levels 2s 2 2p 2 ( 3 P 1 and 3 P 2 ) are better density probes than the next two excited levels 2s 2 2p 2 ( 1 S 0 and 1 D 2 ). Different ions in the same isoelectronic sequence cover not only a wide range of ionization parameters, but also a wide range of density values. On the other hand, within the same isonuclear sequence, those less ionized ions probe lower density and smaller ionization parameters. Finally, we reanalyzed the high-resolution grating spectra of NGC 5548 observed with Chandra in January 2002 using a set of PION components to account for the ionized outflow. We derive lower (or upper) limits of plasma density in five out of six PION components based on the presence (or absence) of the metastable absorption lines. Once atomic data from N-like to F-like ions are available, combined with the next generation of spectrometers that cover both X-ray and UV wavelength ranges with higher spectral resolution and larger effective areas, tight constraints on the density and thus the location and kinetic power of AGN outflows can be obtained.

show abstract

A New Approach to Analyzing Solar Coronal Spectra and Updated Collisional Ionization Equilibrium Calculations. Ii. Updated Ionization Rate Coefficients

Cited by 240 publications

References 36 publications

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Storage ring cross section measurements for electron impact ionization of Fe⁸⁺

Density diagnostics of ionized outflows in active galactic nuclei

Contact Info

Product

Resources

About

A New Approach to Analyzing Solar Coronal Spectra and Updated Collisional Ionization Equilibrium Calculations. Ii. Updated Ionization Rate Coefficients

Cited by 240 publications

References 36 publications

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

Storage ring cross section measurements for electron impact ionization of Fe8+

Density diagnostics of ionized outflows in active galactic nuclei

Contact Info

Product

Resources

About

Storage ring cross section measurements for electron impact ionization of Fe⁸⁺